Update: It appears that this post describes a sponsorship discount (business/school/etc). Those users get a percentage off of their monthly plan ($29.99 voice plan and iPhone data charge excluded). Those who do not see this as an option lack the corporate discount; those who do are seeing what the monthly service cost is after the discount is applied.
Go here to see if you qualify for the corporate discount.
Note that this discount only applies to the voice plan and not to the iPhone data plan. Nor does it apply to the additional lines in a family plan.
Looking to save a little on your monthly iPhone rates? AT&T just announced a price break but you do have to opt-in. It's not automatic. You can save from $6/month on the Nation 450 with rollover up to $12/month on the Nation 1350. The Unlimited plan remains unaffected.
So what's the downside of all this? You may lose some or all of your rollover minutes by converting to the new plan price. So check the fine print before you click Submit. Any existing corporate or student discounts remain unaffected. If you're already receiving a 15% discount, for example, you'll continue to do so after the change. The iPhone data plan for $30 is not altered in any way.
The rate change takes effect immediately. Your current month will be pro-rated up to the date of change, the old charges affecting everything up to your change date, the new charges thereafter. AT&T warns that you may not be able to view your yet-unbilled usage for the remainder of the billing cycle, but you can call and talk to an AT&T representative if you need that information.
[Thanks, Dale Gattis]